He has mastered a 'formidable' amount of material.
The mountains were a 'formidable' barrier.
a 'formidable' enemy/opponent/weapon
(..) I can put my mind to policy, but I'm no good at this brand of politics. Well, if not you, then who? It should be you, Frank. You're formidable. People respect you. They will follow your lead. Let me-- let me be on the sidelines for this. Well, I could only (..)2013 TvShow: House of Cards Title: Chapter 2 Season: 1 Episode 2